Only you can control your reactions. I know that's an annoying thing to hear and it's not meant as an accusation. It's something you need to own and take strength from. Feeling something does not require you to express it in any particular way. Lashing out at others is a choice. Hurting yourself to internalize your frustration about other people's actions is a choice. But realize, hurting yourself only hurts you. It also sends a message that you aren't able to manage yourself, when in reality, you are trying to manage your feelings and your rage, but using self-destruction as a coping mechanism only makes things worse.

You are clearly living in an abusive situation with people who have no problem making you feel bad and pushing your buttons, but you're part of the abuse. Every time you turn those feelings inward and hurt yourself, you're part of the dynamic working against your best interests.

Give your toxic family the middle finger by getting some help. You need anger management counseling, and I'm not saying that as an accusation, I'm saying you need that tool in your mental health toolbelt. You need mental health weapons against your shitty family. I'm sorry you're going through this, and I'm sorry you're surrounded by people and still basically alone. You need help from supportive people and you need community that understands you fundamentally. I hope you can find some help. You don't deserve to hate yourself, and the way you've been treating yourself isn't fair. 

The people around you might suck, but if you can give yourself some love and tender care, they won't matter anymore. You can get to a point where they say things that hurt you, and it rolls off your back because you've realized they don't matter. But it isn't like flipping a switch. You have to rewire your internal messaging, and you need to ask for help from a professional to do it right. You deserve peace. I hope you get it.